Active shutter systems, passive shutter systems and glasses-free systems are known as display technologies for displaying a stereoscopic video.
A typical video system according to the active shutter systems is provided with a display device designed to alternately display a left frame image, which is observed by the left eye, and a right frame image, which is observed by the right eye, and an eyewear device, which assists in viewing the video so as to make the left frame image observed only with the left eye and the right frame image observed only with the right eye. The eyewear device includes a left shutter, which is opened during display of the left frame image and closed during display of the right frame image, and a right shutter, which is opened during the display of the right frame image and closed during the display of the left frame image. The synchronization operation of the left and right shutters with the display of the left and right frame images is achieved by means of control signals which are communicated between the display device and the eyewear device.
Patent Document 1 discloses a video system according to the aforementioned active shutter system. A left field period for displaying a left frame image and a right field period for displaying a right frame image are assigned to a display period for displaying a video. At the switching timing between the left and right field periods, the display device displays a combined image between the left and right frame images. For example, a left frame image combined with a right frame image may be displayed immediately after the start of the left field period whereas a right frame image combined with a left frame image is displayed immediately after the start of the right field period. Patent Document 1 proposes closing the left and right shutters while the combination between the left and right frame images is displayed. Consequently, a viewer may be less likely to view the combined images between the left and right frame images.
The aforementioned active shutter technologies may be applied to other video views than stereoscopic videos. For example, if one display period for displaying a first video representing first contents is assigned to the left field period while another display period for displaying a second video representing second contents, which are different from the first contents, is assigned to the right field period, the display device may time-divisionally display a few videos which are different in contents. If a viewer selects the first video, the eyewear device opens the left and right shutters during the display period of the first video and closes the left and right shutters during the display period of the second video in response to control signals transmitted from the display device. If the viewer selects the second video, the eyewear device opens the left and right shutters during the display period of the second video and closes the left and right shutters during the display period of the first video in response to the control signals transmitted from the display device. Therefore, the viewer may selectively view the first and second videos.
In the following description, a display mode for displaying a stereoscopic video is referred to as “stereoscopic display mode”, and the display mode for allowing a viewer to selectively view the first and second videos is referred to as “dual display mode”.
Patent Documents 2 to 4 disclose video technologies which allow a viewer to select between the stereoscopic and dual display modes. According to these disclosed technologies, the viewer who selects the stereoscopic display mode may view the stereoscopic video. The viewer who selects the dual display mode may view the first or second video.
Video technologies, which allow the selection between the stereoscopic and dual display modes, requires communication of more various control information than video technologies for displaying images only in the stereoscopic display mode. Appropriate acquisition of mode information about the display mode of the display device is required for the eyewear device to accurately operate in response to the display mode of the display device. The eyewear device, which acquires the mode information instructing that the display device operates in the stereoscopic display mode, also has to obtain left open timing information about the open timing of the left shutter, left close timing information about the close timing of the left shutter, right open timing information about the open timing of the right shutter, and right close timing information about the close timing of the right shutter. The eyewear device, which acquires the mode information instructing that the display device operates in the dual display mode, also has to obtain timing information about the display start timing and display end timing of the first video if the viewer selects the first video. The eyewear device, which acquires the mode information instructing that the display device operates in the dual display mode, also has to obtain timing information about the display start timing and display end timing of the second video if the viewer selects the second video.
As described above, in order to provide various control information to the eyewear device, a protocol about control signals, which are communicated between the display device and the eyewear device, has to define various command signals. Usage of various command signals may become a cause of communicative failures between the display device and the eyewear device.
The communicative failures between the display device and the eyewear device may result in various malfunctions in the eyewear device. For example, while the display device operates in the dual display mode, the eyewear device may erroneously interpret that the control information included in the control signals represents the stereoscopic display mode. In this case, the viewer may observe the first video with the left eye and the second video with the right eye. While the display device operates in the stereoscopic display mode, the eyewear device may erroneously interpret that the control information included in the control signals represents the dual display mode. In this case, the viewer may not stereoscopically perceive the video.
Patent Document 1:WO 2007/126904 A
Patent Document 2:JP 10-243420
Patent Document 3:JP 07-222087
Patent Document 4:U.S. Patent Publication 2011/0134231 A